A 5.1-magnitude aftershock rattled New Zealand's Christchurch today, geologists said, reportedly cutting power in some areas of the already earthquake-devastated city.

A 5.1-magnitude aftershock rattled New Zealand's Christchurch today, geologists said, reportedly cutting power in some areas of the already earthquake-devastated city.

The quake struck at 22:34 (local time) at a depth of 10 kilometres (6.2 miles), seven kilometres south west of Christchurch, the US Geological Survey said. The official GeoNet monitoring service said it was felt across the city, which has suffered three major quakes in the past nine months, including a 6.0 tremor on June 13 and February's devastating 6.3 quake that killed 181 people.

Police said there were no reports of major damage from today's quake, although the Christchurch Press and Radio New Zealand said power supplies were down in a number of suburbs. Christchurch resident Farhad Dastgheib told the Christchurch Press that the quake had pushed his bed around violently. "We heard a rumble and thought not again," Dastgheib said. "It didn't last as long as last Monday's quake but still felt scary.

The aftershocks keep coming." GeoNet reported further aftershocks measuring 3.5 and 3.6 in the hour after the 5.1 shake. New Zealand Prime Minister John Key said yesterday the bill from the devastating Christchurch earthquakes had soared to NZ$25 billion (USD 20.2 billion), far more than previously thought.